Abstract

Understanding how dietary and microbial adaptations shape species coexistence is fundamental to ecological and evolutionary research. This dissertation investigates the diet and gut microbiome composition of two sympatric callitrichids, emperor tamarins (Tamarinus imperator) and saddleback tamarins (Leontocebus weddelli), to understand the environmental and dietary drivers of gut microbiome composition, assess mechanisms of niche differentiation and the potential for microbial-mediated resource partitioning. Chapter two investigates the dietary ecology of T. imperator and L. weddelli using fecal DNA metabarcoding to identify the plant, arthropod, and vertebrate taxa in their diets. A key challenge in metabarcoding studies is the reliance on comprehensive barcode reference libraries, which remain incomplete for many Neotropical species. To address this, we generated novel DNA barcode sequences for plant species commonly consumed by primates, improving taxonomic resolution and expanding reference datasets. Using a combination of newly generated DNA barcodes and published reference data, comprehensively characterized the omnivorous diet of these two primate species. This multi-marker approach identified 264 plant genera, 34 arthropod families, and several frog taxa, revealing both substantial dietary overlap and notable interspecific differences. Although both species relied heavily on Cecropia, particularly in the dry season, L. weddelli exhibited a broader dietary range, consuming a greater diversity of plant genera than T. imperator. Seasonal variation in the diet of L. weddelli also showed significant shifts in dominant plant taxa from Cecropia and Philodendron during wet season to Annona, Inga, and Tapirira during the dry season. Arthropod consumption included both actively hunted prey such as Geometridae (geometer moths) and Staphylinidae (rove beetles), as well as small-bodied prey likely consumed incidentally, such as Diptera (flies) and Aphidae (aphids). Vertebrate DNA, primarily from amphibians, was detected in a small subset of samples, suggesting opportunistic predation. These findings highlight the utility of fecal metabarcoding in clarifying dietary diversity and identifying cryptic food sources that are often overlooked in observational studies. In chapter three, we analyzed the gut microbiome composition and its relationship to dietary intake and habitat use. Firmicutes dominated the gut microbiota of both species, indicating a strong reliance on microbes for carbohydrate metabolism. We found that despite their overlapping home ranges, L. weddelli and T. imperator exhibit species-specific differences in their gut microbial communities, however species identity only accounted for a small proportion of microbiome variation (3.37%). Microbial diversity varied across primary, secondary, flooded, and bamboo forests, and home range overlap significantly influenced microbiome similarity between individuals, even when controlling for species identity. Notably, tamarins in secondary forests exhibited increased abundances of Helicobacter, Mycoplasma, and Streptococcus, taxa associated with gastrointestinal dysbiosis in both humans and non-human primates. While previous research indicated that T. imperator is highly adapted to disturbed habitats, our findings suggest that this adaptability may come at a physiological cost, with potential implications for long-term health and survival in fragmented landscapes. We found significant associations between dietary taxa and microbes, indicating that host microbiomes are enriched with taxa that may facilitate the metabolism of specific dietary substrates, or may be transmitted from specific dietary items. These findings highlight the role of gut microbiota in facilitating dietary flexibility, which may be crucial for species persistence in dynamic and disturbed environments, ultimately reducing direct competition and promoting coexistence. In chapter four, demographic factors such as age, sex, and reproductive status were examined as drivers of gut microbiome variation within each species. We observed varying trends between the two species. Juveniles exhibited distinct microbial communities from adults in both species. In L. weddelli, non-breeding females harbored microbial communities enriched with taxa associated with lactate metabolism, while reproductive females had microbiomes enriched with taxa associated with short-chain fatty acid (SCFA) production. In T. imperator, non-breeding individuals had increased Escherichia abundances. Additionally, social group membership emerged as a key determinant of microbiome composition, with network analyses also showing that juveniles shared more microbial taxa with primary breeding males, reinforcing the role of alloparental care in horizontal microbial transmission through close social interaction, such as infant carrying, in these species. Together, these findings demonstrate that dietary specialization, environmental exposure, and social structure shape gut microbiome composition in T. imperator and L. weddelli, reinforcing microbial-mediated niche differentiation. This research underscores the gut microbiome’s role in facilitating dietary adaptability and species coexistence in complex ecosystems. Future work incorporating functional metagenomics could provide deeper insights into the evolutionary and ecological consequences of microbiome variation in wild primates.

Committee Chair

Elizabeth Quinn

Committee Members

Crickette Sanz; Elizabeth Mallott; Emily Wroblewski; Mrinalini Watsa

Degree

Doctor of Philosophy (PhD)

Author's Department

Anthropology

Author's School

Graduate School of Arts and Sciences

Document Type

Dissertation

Date of Award

5-6-2025

Language

English (en)

Author's ORCID

https://orcid.org/0000-0001-6290-1312

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Available for download on Wednesday, May 05, 2027

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Anthropology Commons

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